在 MySQL 中,有多种方法可以查看当前字符集和校对规则。下面是具体的方法及举例:
一、查看当前数据库的字符集和校对规则
可以使用以下命令来查看当前数据库的字符集和校对规则:
SHOW VARIABLES LIKE 'character_set_database';
SHOW VARIABLES LIKE 'collation_database';
例如:
mysql> SHOW VARIABLES LIKE 'character_set_database';
+------------------------+----------+
| Variable_name | Value |
+------------------------+----------+
| character_set_database | utf8mb4 |
+------------------------+----------+
1 row in set (0.00 sec)
mysql> SHOW VARIABLES LIKE 'collation_database';
+--------------------+-----------------+
| Variable_name | Value |
+--------------------+-----------------+
| collation_database | utf8mb4_general_ci |
+--------------------+-----------------+
1 row in set (0.00 sec)
二、查看当前服务器支持的字符集和校对规则
可以使用以下命令来查看当前服务器支持的字符集和校对规则:
SHOW VARIABLES LIKE 'character_set_%';
SHOW VARIABLES LIKE 'collation_%';
例如:
mysql> SHOW VARIABLES LIKE 'character_set_%';
+--------------------------+--------------------------------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------------------------------+
| character_set_client | utf8mb4 |
| character_set_connection | utf8mb4 |
| character_set_database | utf8mb4 |
| character_set_filesystem | binary |
| character_set_results | utf8mb4 |
| character_set_server | utf8mb4 |
| character_set_system | utf8 |
| character_sets_dir | /usr/local/mysql-8.0.23-macos11-x86_64/share/charsets/ |
+--------------------------+--------------------------------------------------------+
8 rows in set (0.00 sec)
mysql> SHOW VARIABLES LIKE 'collation_%';
+----------------------+-----------------+
| Variable_name | Value |
+----------------------+-----------------+
| collation_connection | utf8mb4_general_ci |
| collation_database | utf8mb4_general_ci |
| collation_server | utf8mb4_general_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)
三、查看特定表或列的字符集和校对规则
可以使用以下命令来查看特定表或列的字符集和校对规则:
SHOW CREATE TABLE tablename;
例如:
mysql> SHOW CREATE TABLE mytable;
+--------+-----------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+--------+-----------------------------------------------------------------------------------------------------------------------+
| mytable | CREATE TABLE `mytable` (
`id` int(11) NOT NULL,
`name` varchar(255) COLLATE utf8mb4_general_ci NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci |
+--------+-----------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
这个命令显示了 mytable 表的创建语句,包括表的字符集和校对规则以及各个列的字符集和校对规则。
总之,在 MySQL 中,字符集和校对规则是非常重要的。选择正确的字符集和校对规则,可以确保数据在不同的数据库和应用程序之间的正确交互,并防止出现不必要的问题。可以通过以上的命令和方法来查看MySQL 中的字符集和校对规则。